1. Technical Field
The present invention relates to the field of desalination, and more particularly, to an easy to operate, environment friendly reverse osmosis desalination system.
2. Discussion of Related Art
Overcoming water shortage often requires desalinating water at a high energy expense and at high environmental prices resulting from added chemicals which are returned to the environment.
For example, in reverse osmosis desalination, chemicals are added to the feed seawater to prevent scaling and fouling in the membranes. Such chemicals may include acids and pH regulators, ferric compounds, various antiscalants (scale inhibitors), chlorine, various biocides (e.g. algae killing compounds), etc. Some of the antiscalants serve as nutrients to algae and bacteria, and hence increase biofouling. Some of the chemical additives in the pre-treatment stage are then neutralized by chemicals added at the post treatment stage. Some of the membrane cleaning chemicals are dangerous chemicals, and much of them is expelled in the brine exiting the desalination plant, causing environmental problems. Moreover, some of these materials may reach the final product in cases of local failures in the membrane or in the membrane flushing process.
Handling these chemicals requires extensive logistic efforts and solving of various environmental problems. These difficulties render desalination plants to be large and remote from residential areas to which they supply water.
WIPO Publication No. 2006/057249 discloses a reverse osmosis (RO) system with a pretreatment unit combining a biological active carbon column and a microfilter or an ultrafilter to remove suspended particles, organic matter and microorganisms from the seawater.